The present disclosure relates to a printed circuit board connected to a battery, and more particularly, to a printed circuit board having an improved structure connected to an electrode led out from a battery.
Recently, the technology development and demand for mobile apparatuses, electric vehicles, hybrid vehicles, power storage devices, and uninterruptable power supply devices have increased, and thus, the demand for secondary batteries as energy sources have been rapidly increasing.
In particular, battery packs used for electric vehicles and hybrid vehicles are high-power, high-capacity secondary batteries, and much research thereon has been carried out.
In general, the secondary batteries mean chemical batteries which can be repeatedly charged and discharged by using reversible mutual conversion between chemical energy and electrical energy.
Since various flammable materials are contained in such secondary batteries and there is a danger of being heated, exploded, or the like due to overcharge, over-current, external physical shock, or the like, the secondary batteries have a drawback of having weak safety.
Accordingly, the secondary batteries are configured such that a battery cell is connected to a printed circuit board on which safety elements, such as a positive temperature coefficient (PTC) element or a protection circuit module, is mounted so as to effectively control abnormal states such as overcharge, over-current, or the like.
FIG. 1 is a plan view schematically illustrating a structure of a conventional printed circuit board, and FIG. 2 is a side cross-sectional view illustrating connection between a conventional printed circuit board and a battery.
Referring to FIGS. 1 and 2, a thin plate-shaped metal plate 5 is mounted on a connection part 8 of a printed circuit board 3, an electrode lead 2 of a battery 1 is stacked on the metal plate 5, and then the electrode lead 2 of the battery 1 is welded to the metal plate 5 to form connection.
At this point, as illustrated in FIG. 2, the region in which the metal plate 5 and the electrode lead 2 of the battery 1 are welded corresponds to the portion in which the metal plate 5 is mounted on the printed circuit board 3.
In general, when mounted on the printed circuit board 3, the metal plate 5 is bonded by soldering using a solder 4.
When the metal plate 5 and the electrode lead 2 of the battery are welded through such soldering, as described above, the welded region overlaps the soldering region, and thus, the solder 4 in the soldered portion is melted due to a temperature rise caused by electrical limitations such as unstable current or voltage during the welding.
In addition, such a melted solder is scattered around due to the pressure of a welder, and the solder scattered as such is also scattered to the electrode lead 2 of the battery 1 and unintentionally connected to the electrode lead 2 of the battery 1, and thus, there is a limitation in that a short circuit is caused.
To prevent such a limitation, there is a method of forming the metal plate to have a great thickness, but in this case, there is a drawback in that entire thickness increases due to the increase in the thickness of the metal plate, and the miniaturization and simplification of components cannot be achieved.